Boxwood plant named `Green Ice`

ABSTRACT

A new and distinct Buxus cultivar of unknown parentage is provided that is believed to be an interspecific cross. The attractive medium-sized evergreen shrub exhibits a dense upright mounded and compact growth habit. No pruning is required to maintain the compact and mounded growth habit. The glossy foliage is deep olive green throughout the year and exhibits no substantial change in coloration during the winter. The winter hardiness also is exceptionally good. The new cultivar accordingly is capable of providing attractive ornamentation in the landscape even during the coldest winter months. No fragrance is emitted by the foliage. An unusually rapid growth cycle is possible following propagation which renders the new plant well suited for commercial production in containers.

SUMMARY OF THE INVENTION

The present invention relates to a new and distinct Buxus cultivar thatwas discovered and selected during about 1964 at Portage, Pa. The exactparentage of the new cultivar is unknown. It is assumed that it may bean interspecific hybrid in view of the combination of characteristicsexhibited by the new cultivar. Likely parents of the new cultivar arebelieved to be Buxus sempervirens `Suffructicosa`×Buxus microphyllakorena (i.e., Korean Box).

A single plant of the new cultivar was discovered, selected, andpreserved having the distinctive characteristics discussed hereafter.Had the new cultivar of the present invention not been found andpreserved, it would have been lost to mankind.

Upon careful observation and testing, the new cultivar of the presentinvention was found to express the following combination ofcharacteristics:

(a) assumes a dense upright mounded and compact growth habit,

(b) forms deep olive green foliage throughout the year without anysubstantial coloration change during the winter,

(c) exhibits excellent winter hardiness to at least U.S.D.A. Plant --Hardiness Zone 4,

(d) lacks a typical Boxwood foliage fragrance, and

(e) exhibits an unusually rapid growth cycle following asexualpropagation from a cutting.

The new cultivar is a dense upright mounded compact woody broad-leafevergreen that is capable of being grown as an attractive ornamentalplant throughout the entire year. The deep olive green coloration of thefoliage is well maintained even during the winter and unlike manypreviously available Boxwood cultivars it well resists a tendency toassume a brownish-green foliage coloration during the winter. Goodresistance to winter burn is exhibited. The hardiness of the newcultivar also equals or exceeds that of most previously known Boxwoodcultivars that are known for superior hardiness. No blossoms or fruitshave been observed to form on the new cultivar to date. Also, thefoliage is found to be lacking in fragrance unlike typical Boxwoodshrubs. Such absence of fragrance will be considered preferable by somegrowers.

The new cultivar can be grown to advantage as attractive ornamentationin the landscape, and is particularly well suited for use in theformation of low-growing hedges or edge plantings. No pruning isrequired to maintain the illustrated dense and compact growth habit. Thenew plant of the present invention commonly assumes a height thatexceeds its width. Also, the new cultivar has been found to perform wellin sun or shade in many soil types including those containing clay.

The new cultivar has been tested at Portage, Pa. since about 1964, atthe Morton Arboretum at Lisle, Ill. since 1980, and at West Grove, Pa.since 1991.

When compared to the `Green Velvet` cultivar (non-patented in the UnitedStates), the new `Green Ice` cultivar exhibits a more upright growthhabit, and unlike the `Green Mountain` cultivar, the new `Green Ice`cultivar exhibits a good retention of green foliage coloration duringthe entire year including the coldest winter months.

The rapid growth cycle of the new cultivar is particularly noteworthy.For instance, attractive compact plants produced from cuttings intwo-gallon containers commonly assume a height of 11/2 to 2 feet withintwo years following asexual propagation.

Asexual reproduction of the new cultivar by the use of cuttings has beencarried out at Portage, Pa., and at West Grove, Pa. Such propagation hasconfirmed that the unique combination of characteristics of the newcultivar has been stably established and is well transmitted tosuccessive generations.

The new cultivar has been named `Green Ice`.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show as nearly true as it is reasonablypossible to make the same, in color illustrations of this character,typical specimens of the new cultivar.

FIG. 1 illustrates a mature plant of the `Green Ice` cultivar duringJune 1990 while being grown in the landscape for test purposes at theMorton Arboretum, Lisle, Ill. The plant had been planted at the MortonArboretum during the Spring of 1986. The uniform upright mounded andcompact growth habit in the absence of pruning is illustrated.

FIG. 2 illustrates in the background at the left-center during June1990, the same `Green Ice` plant of FIG. 1. Typical Boxwood plants areshown in the foreground having lower more spreading growth habitscombined with substantial winter damage. The `Green Ice` plant iscompletely free of winter damage when grown under the same conditions.

FIG. 3 illustrates a young plant of the `Green Ice` cultivar during theSpring of 1997 when growing in the landscape at West Grove, Pa. Suchplant was originally grown in a container and was transplanted to thelandscape during the Fall of 1996. The illustrated plant wasapproximately two years of age and had already assumed a height ofapproximately 11/2 to 2 feet.

FIG. 4 illustrates a closer view of the typical old and new foliage ofthe `Green Ice` cultivar during the Spring of 1997 that was formed on ayoung plant being grown in the landscape at West Grove, Pa. Theattractiveness of the deep green spring flush is apparent.

DETAILED DESCRIPTION

The following is a detailed description of the new cultivar of thepresent invention which was prepared while observing five year-oldplants growing in containers at West Grove, Pa. Color terminology is inaccordance with the R.H.S. Colour Chart of The Royal HorticulturalSociety, London, England, except where general terms of ordinarydictionary significance are used.

Type: Hardy broad-leafed evergreen shrub for garden decoration andgeneral landscape use.

Botanical classification: Buxus hybrid, `Green Ice` cultivar of unknownparentage.

Growth habit: Medium growing, dense, compact, and upright mounded. Theplant height commonly exceeds the plant width. A more rapid growth cyclethan most other Buxus cultivars commonly is observed.

Plant dimensions: A five year-old plant commonly assumes a height ofapproximately three feet and a width of approximately two feet, and afully mature plant commonly assumes a height of approximately four feetand a width of approximately three feet.

Propagation: It holds its distinguishing characteristics throughsucceeding propagations by asexual propagation methods, such as therooting of vegetative cuttings.

Juvenile foliage:

Size.--Approximately 2 cm. in length on average.

Shape.--Lanceolate with a cuneate base and an acuminate apex.

Margin.--Entire.

Winter color.--Upper surface: Yellow-Green Group 147A. Lower surface:Between Yellow-Green Group 144B and 144C with a midrib of Grayed-YellowGroup 161D.

Spring color.--Upper surface: Yellow-Green Group 144A. Lower surface:Yellow-Green Group 144C with veins of Yellow-Green Group 144A.

Summer color.--Upper surface: Green Group 139A. Lower surface:Yellow-Green Group 144A with margin of Green Group 137A, and a midrib ofYellow-Green Group 145A.

Fragrance.--None.

Mature foliage:

Size.--Approximately 2.5 cm. in length on average.

Shape.--Lanceolate with a cuneate base and an acuminate apex.

Margin.--Entire.

Winter color.--Upper surface: Yellow-Green Group 147A. Lower surface:Between Yellow-Green Group 146B and Yellow-Green Group 146C with amidrib of Grayed-Yellow Group 160D.

Spring color.--Upper surface: Yellow-Green Group 144A. Lower surface:Yellow-Green Group 144C with veins of Yellow-Green Group 144A.

Summer color.--Upper surface: Commonly between Green Group 137A andGreen Group 139A. Lower surface: Yellow-Green Group 144A and 144B with amidrib of Yellow-Green Group 145C.

Petioles.--Size: Commonly approximately 0.25 cm. in length on average.Color: Yellow-Green Group 146D with highlights of Grayed-Orange Group163C.

Fragrance.--None.

Juvenile branches:

Color.--Yellow-Green Group 144B with striations of Green Group 143B.

Diameter.--Approximately 0.25 cm. on average.

Mature branches:

Color.--Green Group 143C with striations of Grayed-Yellow Group 161C.

Diameter.--Approximately 1 cm. on average.

Inflorescence: No flower or fruit production has been observed to date.

Development:

Hardiness.--Is believed to be hardy to at least U.S.D.A. Plant --Hardiness Zone 4. The new cultivar has well withstood wintertemperatures as low as -16° F. combined with significant wind forces atWest Grove, Pa., with no sign of foliage burn.

Disease resistance.--No disease problems have been observed to date.

Insect tolerance.--No insect damage has been observed to date.

It is claimed:
 1. A new and distinct variety of Buxus hybrid plantpossessing the following characteristics:(a) assumes a dense uprightmounded and compact growth habit, (b) forms deep olive green foliagethroughout the year without any substantial coloration change during thewinter, (c) exhibits excellent winter hardiness to at least U.S.D.A.Plant -- Hardiness Zone 4, (d) lacks a typical Boxwood foliagefragrance, and (e) exhibits an unusually rapid growth cycle followingasexual propagation from a cutting;substantially as herein shown anddescribed.